Plasma chambers are used to perform a variety of processes, e.g., etching, depositing, etc. For example, a gas is supplied to the plasma chamber when power is supplied to the chamber. Plasma is stricken when the power is supplied while the gas is in the plasma chamber. The plasma is used to etch a substrate or to clean the plasma chamber. Also, materials are deposited on the substrate by using liquid or gas flows into the chamber.
However, controlling the processes is a difficult task. For example, the materials on the substrate are etched too much or too little. As another example, layers deposited on the substrate have a greater thickness than that desired or have lesser thickness that that desired.
It is in this context that embodiments described in the present disclosure arise.